#include<iostream>
#include<iomanip>
#define pi 3.14
using namespace std;

int main()                        //计算球的体积
{
    int r ;
    cin >> r;
    double v = (4.0/3.0)*pi*r*r*r;
    cout << fixed << setprecision(5) << v << endl;
    return 0;
}